1. Field of the Invention
The present invention relates to a container and a method of unloading and receiving material from such a container. More particularly, The present invention relates to a container having an inner bag unloading mouth which prevents contamination and mixing of the filled material with foreign matters when the filled material is unloaded, a container receiving sleeve cap for receiving the filled material from the unloading mouth, and a process of unloading and receiving the filled material using the container and the sleeve cap.
2. Description of the Related Art
In the past, containers such as 25 kg package bags, 500 kg.about.3 metric ton flexible containers, 10.about.30 m.sup.3 volume box type rigid containers, 500 kg.about.4 metric ton specialized metal containers and 10.about.20 metric ton specialized hopper cars have been utilized to store and transport large quantities of materials including pellets and powder. However, in recent years, the use of such storage containers has been questioned as a result of changing social circumstances that demand quality assurance and environmental conservation. For example, the use of package bags has created economic problems as a result of the labor costs associated with the filling, packing, opening and unloading of each individual bag. Environmental problems have also ben created by these bags. The environmental problems focus on the mass of package waste caused by the empty bags and the environmental effects of the treatment processes needed to dispose of the empty bags. Additionally, when these package bags are opened, foreign matter can mix with the contained material and contaminate it. As a result, the use of package bags also raises handling and contamination issues.
Filling specialized metal containers and specialized hopper cars using inert gases under pressure can prevent the filled material, such as pellets, from becoming contaminated by foreign matter during transportation. However, unless each container or hopper car is used only to carry one type of filling material, cross-contamination can still take place. By limiting each container or hopper car to only carrying one type of material, the versatility of the container or hopper car is significantly decreased while the number of them that must be constantly maintained is increased. In addition to the cost of these expensive containers, specialized unloading and receiving facilities with expensive equipment are required to avoid the contamination and mixing of the filled material with foreign matters during unloading.
Even though the 10.about.30 m.sup.3 volume box type rigid containers can be used to transport generalized loads, inner bags must be positioned within each container to prevent cross contamination. These bags can increase the difficulties associated with loading and unloading the containers. For example, it is difficult to completely unload the filled material from a side face on the rear door of the container when an inner bag is used. Furthermore, as with the specialized metal containers and specialized hopper cars mentioned above, after being unloaded, the box type rigid containers are returned empty. The costs and labor required to return the empty containers make them economically impractical. This is especially true when the containers are used to export materials.
On the other hand, so-called flexible containers have been used because they are flexible, economically advantageous and able to function without an inner package bag. However, these flexible containers have problems with contamination and cross-contamination. However, in recent years, various improvements to flexible containers have been examined. For example, laid-open Japanese patent 10391/1996 discloses a flexible container having a double layer structure for preventing contamination and cross-contamination during transportation. The double layer structure includes a flexible inner bag positioned within an outer shell formed by a durable sheet material that is contamination-proof, oxidation-proof, and moisture-proof. The bag material can include a polyethylene film or a polyethylene laminated film.
Recently, a rigid one way container having an outer shell with a corrugated board or wooden frame has been used as an exporting container. This rigid container is similar to the above discussed flexible container, except the outer shell of the flexible container has been replaced by a rigid shell. These flexible and rigid one way containers are loaded on pallets that can be moved by general lifters and palleters. As a result, no specialized facility is required when these containers are received.
In the cases of pellets or other products which require high purity and minimal contamination during transportation, the flexible or rigid one way container mentioned above (both of these containers are hereinafter collectively referred to simply as "container" in this specification) are commonly filled in a plant that is well-equipped to control and prevent contamination during the filling process. However, there have been problems concerning contamination or mixing of the filled pellets with foreign matter while the pellets are being unloaded and received into a receiver tank after being transported to their final location. Therefore, it has been recommended to open and unload containers in a "clean room." However, even when a clean room is used, it is difficult to completely eliminate the dust that adheres to the outside of the containers during transportation. As a result, the clean rooms are not always effective. Additionally, the clean rooms need to be large-scale and require the construction of expensive facilities. Because of the costs associated with clean rooms, they have not been considered an economically feasible option.
Additional contamination problems can occur during the opening of the flexible inner bags. For example, when a pair of scissors are used for unsealing the unloading section of a sealed inner bag, cross-contamination with contaminants adhered to the scissors can occur. Additionally, metal fragments created by the friction between the cutting blades of the scissors may enter the inner bag and contaminate the contained material. This is especially troubling when the contained material includes plastic pellets for insulating electrical wires. If the metal fragments contaminate the plastic pellets, the performance of the wires can be adversely affected.